Mesa (master): i965: Fix gen6 pixel_[xy] setup to avoid mixing int and float src operands.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 0cadd32b6dc80455802c04b479ec8e768f93ffe1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=0cadd32b6dc80455802c04b479ec8e768f93ffe1

Author: Eric Anholt <eric at anholt.net>
Date:   Mon Oct 11 15:24:12 2010 -0700

i965: Fix gen6 pixel_[xy] setup to avoid mixing int and float src operands.

Pre-gen6, you could mix int and float just fine.  Now, you get goofy
results.

Fixes:
glsl-arb-fragment-coord-conventions
glsl-fs-fragcoord
glsl-fs-if-greater
glsl-fs-if-greater-equal
glsl-fs-if-less
glsl-fs-if-less-equal

---

 src/mesa/drivers/dri/i965/brw_fs.cpp |   21 +++++++++++++++------
 1 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 35ec79e..3d53d9d 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -1579,19 +1579,28 @@ fs_visitor::emit_interpolation_setup_gen6()
 
    /* If the pixel centers end up used, the setup is the same as for gen4. */
    this->current_annotation = "compute pixel centers";
-   this->pixel_x = fs_reg(this, glsl_type::uint_type);
-   this->pixel_y = fs_reg(this, glsl_type::uint_type);
-   this->pixel_x.type = BRW_REGISTER_TYPE_UW;
-   this->pixel_y.type = BRW_REGISTER_TYPE_UW;
+   fs_reg int_pixel_x = fs_reg(this, glsl_type::uint_type);
+   fs_reg int_pixel_y = fs_reg(this, glsl_type::uint_type);
+   int_pixel_x.type = BRW_REGISTER_TYPE_UW;
+   int_pixel_y.type = BRW_REGISTER_TYPE_UW;
    emit(fs_inst(BRW_OPCODE_ADD,
-		this->pixel_x,
+		int_pixel_x,
 		fs_reg(stride(suboffset(g1_uw, 4), 2, 4, 0)),
 		fs_reg(brw_imm_v(0x10101010))));
    emit(fs_inst(BRW_OPCODE_ADD,
-		this->pixel_y,
+		int_pixel_y,
 		fs_reg(stride(suboffset(g1_uw, 5), 2, 4, 0)),
 		fs_reg(brw_imm_v(0x11001100))));
 
+   /* As of gen6, we can no longer mix float and int sources.  We have
+    * to turn the integer pixel centers into floats for their actual
+    * use.
+    */
+   this->pixel_x = fs_reg(this, glsl_type::float_type);
+   this->pixel_y = fs_reg(this, glsl_type::float_type);
+   emit(fs_inst(BRW_OPCODE_MOV, this->pixel_x, int_pixel_x));
+   emit(fs_inst(BRW_OPCODE_MOV, this->pixel_y, int_pixel_y));
+
    this->current_annotation = "compute 1/pos.w";
    this->wpos_w = fs_reg(brw_vec8_grf(c->key.source_w_reg, 0));
    this->pixel_w = fs_reg(this, glsl_type::float_type);